OFDM is a transmission technique that divides data into a number of orthogonal carriers, and the data is transmitted in parallel overlapping the carriers to thereby minimize space between the carriers. The OFDM system is efficient in complementing radio channel impairments, such as multipath fading, interchannel interference, and noise, etc. Recently, OFDM is being applied for fixed and mobile digital transmission including high resolution television broadcasting.
In an OFDM-based multi-cell environment, a terminal receives a signal transmitted from base stations respectively covering different cells. In particular, all the base stations synchronize signal transmission using a global positioning system (GPS) such that the terminal almost synchronously receives signals from a base station of a cell in which the mobile terminal is located (“hereinafter referred to as a “current cell”) and a base station of a neighbor cell.
Since a mobile terminal of a synchronous OFDM system receives signals transmitted from several different cells in the multiple-cell environment, the mobile terminal obtains much information by demodulating signals transmitted from the base station of a current cell and neighboring cells.
Korean Patent Publication No. 10-2004-0045996 (entitled “Method and apparatus for embodying and synchronizing downlink signal in mobile communication system and method for searching cell using the same”), filed and published from the same laboratory, discloses a method for searching information on an associated base station and a neighbor cell. However, this prior art describes a method for searching information on a base station of a current cell and a neighbor cell in a multi-cell environment rather that describing a method for demodulating signals transmitted from the base station and the neighbor cell.
In addition, conventionally, a structure of a mobile terminal is complicated because multiple FFT operations are performed to receive signals from a current cell and its neighbor cells, and precise control of synchronization and the FFT operations is also required in consideration of the multi-cell environment. The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention, and therefore, unless explicitly described to the contrary, it should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art.